Ammeter.



'P. NIL-LINCOLN.

AMMETER.

APPLICATION FILED MAY 16. I914- Patented Dec. 4,1917. I

2 SHEETS-SHEET 1.

P. M. LINCOLN.

AMMET'ER. APPLICATION FILD MAYIB. 191'4.

Patented. Dec. 4:, 191?.

2 SHEETSSHEET 2- FEM Vii-P HEM.

.INVENITOR AMMETEFJ.

Specification of Letters Patent.

Patented Dec. a, tort,

Application filed May 16, 1914. Serial No. 839,051.

To all whom it may concern:-

Be it known that 1, PAUL M. LINCOLN, a citizen of the United States, residing at Pittsburgh, in the State of Pennsylvania, have invented certain new' and useful'Tmprovements in Ammeters,of which the following is a specification.

My invention relates particularly to instruments for measuring electric current and is primarily designed to provide asensitive andaccurate current meter; in addition to which 1 provide means for making the response or indication slow so that at any instant the indication is due to the average current that has passed for a certain given time. For this reasonthe device may serve as a maximum demand meter also. In the construction I employ the prlnciple of the heating effect of current'traversing a conductor, and by using twoduplicate members.

, the inside mechanism, certain parts being re- 7 moved; Fig. 2 is an outside face view from j the same direction, showing the dial pointers; Fig. 3 is a central vertical section of the casing ofthe instrument, a partial side elevation of the inside mechanism being shown at right angles to the-view of Fig. 1 and from the right; Fig.4 is a: partial bottow view of the casing showing the opening for setting the pointers and Fig. 5 is a crosssection of the actuatingicurved tubes.

Referring first to Fig. l, 1 provide apair of expansion tubes 6 and 7, identically alike,

bent in the form shown, and being of crosssection asshown in Fig. 5 and filled with a highly expansible liquid such as o1l'or finer-,-

cury or xylene or toluene. Thebent tube 6 is olelicatelyand fixedly pivoted at 8, to a stud in the casingand its upper end is free to move except that its end is attached by a pivot 9 to the upper end of the duplicate tube 7 and to one end of a link bar 10 pivoted at 11. The tube 7 at its lower end is likewisepivoted to a link bar 12, pivoted at '13, and also carries a link 14 which at its top is pivoted to a rocking gear sector 15 pivoted at 8 on the fixed stud, carrying the.

lower end of tube 6.

"from the binding post 16 by flexible loads 17 and 18, through the expansi-ble tube 7, I

as shown, back to the other binding post 19. Itwill be evident that the passage of the current through or around the tube 7 W111 heat it, cause the fluid therein to expand and therefore tend to straighten out the bent tube. By reason of the control of the l1nks 10 and 12, and the attachment of the upper end of tube7 to the tube 6, it is evldent that the pivot point 14 at the lower end of the tube 7 will move virtually in a vertical-direction, thereby rotating the sector 15 by the link 14.

Evidently any changes of temperature in the tubes 7 and 6, which are common to both, will have, no effect in moving the sector 15, since an equal and simultaneous ex pansion or contraction of both tubes 7 and 6 will have no other efiect than to cause a as a path for the current, or otherwise it might be insulated and awire wound over-its 1 outside.

Referring more particularly to Fig. 3, the pivoted sector 15 has its teeth engaged with a gear pinion 20 fixed on the shaft 21 of the indicating pointer 22, which travels over a proper scale on the dial plate 23. I provide a spiral spring 24, (Fig. 1) to keep the back-lash of gears, pivots, links, etc.,.always in the same direction While the zero position of the pointer is adjusted by adjustment of pansion of the tube 7, a second pointer 28 (Figs. 2 and 3), which is attached'to a tube 29 loosely surrounding the pointer shaft 21.

The pointer 28 is provided with a light friction by means of a sprin washer 30, so that it will remain at the hig est point to which it has been pushed by engagement with pointer 22 in the usual way. In order to reset this maximum demand pointer 28, 1 provide the tube 29 with a bevel gear 81 to be engaged bv another bevel gear 32 on the v keyfshaft 3 3 and normally-held out of mesh .by'spiral spring 34. The key shaft 33 is reached through a small door 35 in the bot tom of the casing as shown in Fig.4, and to preve'ntlunauthorized tampering I provide a studded has p 36 passing throu h a slot used.

. tion.

Both the pointersare-icounterbalanced so as tobe .supported' at'thelcenter of gravity, which preventsthe fointer 28 especially from creeping under.

The change of distane of tube 7 can be made directly proportional to theftempe'rature change, and it being understood that the heat produced by the current through the tube. isproportional to the square of the" current,-;I -make the move- "ment of the pointer QQ-mfore nearl proportional to the current insteadof t e square of the current, by use of the'link motion and proportions as shown. Preferably the pivot 14: should have amotion s'uchthat-the sector 15 is causedto turn through an angleof about 90; Evidently motion at and near the no load position will cause a considerably greater motion of the pointer than the same' amount of movement would do at, or near full load condition. This effect is obtained" bythe use of the sector 15 and the link 12, so

-, that the scale divisions on the dial may be made more even. i

'Itwill thus be seen that in my device the ammeter pointer will not move with any change of temperature, except that due to the passage of current through the tube 7 and that the full movement of the pointer will not take place until some time has elapsed, so that the position at any time will indicate the average current that has passed fora given previous length of time. The response may obviously be made slower by changing the liquid therein, by. loading the tubes with extra weight, as by wire windings 7 a ormaking them of greater dimensions.

The time. of response. follows a logarithmic curve; that is, if a given load is thrown on the. instrument, the indication approaches its finalvalue along a logarithmic curve with respect to time. The time-to reach a given proportion of its final value depend ..upon the relation of the radiating surface of the tube -7 to its heat storage capacity. By

changing either of these quantities, the time of response may be modified.

The instrument is adjustable in all parts and simple and accurate in constructiomfand I regard the principal advantages as'restingupon the use of the like pair of expansible bars arranged to indicate their relative expansion due'solely to'the passage of the current to be measured, together with the provision for adjusting and accurately determining the time'lag, and use of the mechain the door 35, so that a padloc can be egsbetween the ends nism shown for exaggerating the readings of the scale at low amperageposition of the pointer. I

. Having thus described my invention and its use, I claim the following:

i 1. A measuring instrument comprising two fluid-containing similar expansion members pivoted together at one of their ends,

one end of one of the members being pivoted to a stationary member, a polnterconnected to the free endof. the other member, and

means for modifying the time of response 'of the pointer by varying the relation between the heat-storage capacity-and the radiating ability of one of the members. 2. In an ammeter, the combination with a dial and a pointer, of two U-shape expansion' elements of like construction pivoted together at one of their ends, the other end ofv one of said elements being fixedly pivoted and the other end of the other element being connected by gearing to the said pointer,

'one of the said elements being adapted to be 'of the tubes.

heated by the current to be measured, and

means for adjusting the time-lag between the passage of the heating current and the response of the indicator, substantially as described. r

. 3. An ammeter comprising two fluid-containing hollow expanslon tubes ofsubstan- ,tially U-shape adaptedto be pivoted together at one of their ends, one end of one of the tubesbeing pivoted to a stationary member, a pointer operatively connected to' the free end of the other tube, and means for modifying the'time-lag of the pointer by varying the relation between the heat-storage capacity 4. An ammeter comprising two operatively connected expansion tubesone of which is pivoted at'o'ne of its ends to a stationary member, a pointer operatively connected to one end of one of-the tubes, one of the said tubes being adapted to be heated in accordance with the current to be measured,

and a plurality of adjustable pivoted links adapted to be attached to the ends of the said heated tube for varying the normal position of the pointer.

5. In an ammeter, the combination with a dial and pointer, of an expansible tube of liquid bent into general U-shape and having.

and the radiating ability of one pivoted to the free end of the first, and a gearing connecting the pointer with its other end and adapted to produce relatively greater movement of the pointer in the vicinity of the noload position of the pointer, said expansion tubes being provided with means for adjusting the relation between t'heir heat absorbing and heat radiating capacities, substantially as described.

7. In a n'ieasuring instrument, the combi- 8. A measuring instrument comprising.

two fluid-containing oppositely disposed expansion tubes, one of which is fixedly piv- 4 oted at one of its ends, a pointer, means for operatively connect ng the polnter to one end of the second tube, the remaining ends .Of the said tubes being pivotally connected together, one of the said tubes being adaptedto be heated in accordance with the quantity to be measured, and a plurality of adjustable pivoted links adapted to be pivot ally attached to the ends of' the said second tube to vary the normal position of the pointer.

9. An ammeter comprising a pointer, two similar expansion members of substantially U-shape pivoted together at one of their ends, the other end of one of the members being-pivoted to a stationary memberand tilt the other end of the other member being operatively connected to the pointer, one of the said members'being adapted to be heated in accordance with the current to be measured, and means for adjusting the time-lag between the passage of the heating current and the response of the pointer.

10. An ammeter comprising a pointer, two similar expansion members of substantially U-shape pivoted together at one of their ends, the other end of one of the members being pivoted to a stationary member and the other end of the other member being operatively connected to the pointer, one of the said members being adapted to be heated in accordance with the current to be measured, and means for so changing the relation between the radiating surface of one of the members to its heat storage capacitv that the lili tltl

time-lag between the passage of the heating current and the response of the pointer may be, any predetermined value.

11. An ammeter comprising two fluidcontaining hollow expansion tubes of substantially Urshape adapted to be pivoted together at one of their ends, one end of one of the tubes being pivoted to a stationary member, apointer operatively connected to the free end of the other tube, and means for modifying the time-lag of the pointer by varying the relation between the heat storage capacity and the radiating ability of the tube that is operatively connected to the pointer.

In testimony whereof I have hereunto signed my name in the presence of the two subscribed witnesses.

PAJUL M. LINCOLN.

Witnesses:

' Jo. BAILY Bnowu, FlREDK. brace, 

